An image forming apparatus having color copying capability is provided with photosensitive drums for yellow, magenta, cyan and black colors. A laser beam is applied to the surfaces of these photosensitive drums, and electrostatic latent images are formed on the surfaces of the photosensitive drums. The electrostatic latent images are developed with developers for the yellow, magenta, cyan and black colors, and become visible images. The visible images are transferred to a transfer belt, which is moved in making contact with the surfaces of the photosensitive drums. The visible images of each color transferred to the transfer belt are transferred to a paper sheet. The transferred paper sheet is sent to a heating roller. The heating roller heats the paper sheet to fix the visible image transferred to the surface of the paper sheet. The transfer belt is pressed to the surfaces of the photosensitive drums by transfer rollers.
In such an image forming apparatus, the transfer belt is moved continuously even after the visible image is transferred to a paper sheet, until the unnecessary developer remaining on the transfer belt is eliminated by a cleaner. As the movement of the transfer belt is continued, the rotation of the photosensitive drum contacting the transfer belt is also continued.
A cleaning blade contacts the surface of each photosensitive drum, and eliminates the unnecessary developer remaining on the drum surface. Thus, if the rotation of the photosensitive drum is continued, the photosensitive drum surface becomes unnecessarily worn and the drum life is reduced.
Moreover, a developing roller of a developing unit contacts the surface of each photosensitive drum. The developing roller supplies developer to the surface of the photosensitive drum while rotating together with the drum. Thus, when the rotation of the photosensitive drum is continued, the developing roller is rotated unnecessarily causing unnecessary shift and stir of the developer, and the developer is degraded unnecessarily.